Submarine signaling cable



o. EQ BUcKLEYf SUBMARINE SIGNALING CABLE Filed June 29, 1931 2Sheets-Sheet n y. m RE m OL wm n M IEW. 0. Qld Vl B Oct. 4, 1932.

4, 1932. E 'BUCKLEY 1,880,764

SUBMARINE SIGNALING CABLE Filed June 29. 1931 2 Sheets-Sheet 2 /O 5HARMOR 8 JUTE ,2 /NsULA T/ON 5 l I LOAM. 7 /NSULATO 3 m7. /NsULAT. 6 T RELOADO.

RETURN TAPE 4 T CONUGTOR /NSULAT/ON 2 CENTRAL CONDUCTOR /o ARMOR 9 a /3F/G 7 /NsULA TEO R ULM/0^', RETURN CON/:uc TOR I INSULTED LOAOOMAT 7LA716 /NsULATa 7' TAPE 7 RE TURN CONDUCTOR T4 PE CENTRAL /NVENTOR OEBUCKLEY A TTORNE Y Patented Oct. 4, 1932 UNITED STATES PATENT OFFICEOLIVER E. BUCKLEY, OF MAPLEWOOD, NEW JERSEY, ASSIGNOR TO BELL TELEPHONELABORATORIES, INCORPORATED, 0F NEW YORK, N. Y., .A CORPORATION 0F NEWYORK SUBMARINE SIGNALING CABLE Application led June 29, 1931, Serial No.547,690, and in Great Britain August 13, 1930.

The present invention relates to signaling cables and more particularlyto submarine signaling cables of the concentric return type.

An object of the invention is to prevent extraneous inductive and otherdisturbances of both high and low frequencies from interfering with theintelligibility of signals transmitted over long submarine cables.

A' further object of the invention is to increase the signal to noiseratio of currents received from the terminals of long submarinesignaling cables.

A further object ofthe invention is to reduce the power level at whichintelligible signaling waves may be received at the receiving end ofsignaling cables having a high attenuation.v

l Inapplicants application, Serial No. 392,- 351, filed September 13,1929 there has been described a method of and means for reducing theeffect of external disturbances upon a long deep sea signaling cable toa level below that of the resistance noise level of the cableconductors,without impairing the flexibility of the cable, by providing between theconcentric return conductor and the armor Wire a wrapping of tapes orWires constituting a sheath of magnetic material of high initialpermeability forming a magnetic path around the inner conducto-rs, andin cases where the external interference is more severe, by applyingoutside this shield a sheath of high electric conductivity forming alongitudinal conductor which is in turn surrounded by a magnetic sheath,or, in special cases, by ,providing a plurality of magnetic sheathsalternating with highly conductive sheaths.

This type of shielding may be looked upon as inductive loadingI of thecurrent path through the armor wire and sea Water since it raises theimpedance for that part of the return circuit which is outside of thecopper returnv conductors and this is the meaning of the term loading asapplied herein to the result of the provision of a sheath or sheaths ofmagnetic material external to the concentric copper return conductor.This loading. is obviously most effective (to cause the return currentto flow in the copper return conductor rather than in the armor and/orsea water) at relatively high frequencies since the impedance added by adefinite amount of inductive loading increases in proportion to thefrequency. At very low frequencies such as in the range of low frequencytelegraphy the effectiveness of this means of shielding is reduced.

The object of the present invention is to provide effective shieldingfor both high and low frequency electrical disturbances of terminalportions of long deep sea submarine telephone cables of the concentricreturn type.

To this endthe invention contemplates a submarine cable, or sectionthereof, comprising a continuously loaded central conductor and aconcentric return conductor continuously surrounded by magneticmaterial, wherein the return conductor or at least part thereof, incases where the return conductor is partly formed by the metallicarmoring of the cable, is insulated to shield the insulated part of thereturn conductor from low frequency electrical disturbances.

In the preferred embodiment the invention comprises a submarine cableterminal section comprising a continuously loaded central conductor anda concentric return conductor continuously surrounded by magneticmaterial, wherein the return conductor is insulated as well as beingloaded so as to be shielded for both hiOh and low frequency electricaldisturbances.

According to one feature of the invention, the cable may comprise acentral conductor surrounded by loading tape and insulation in the usualmanner. This insulation may be provided with a wrapping of toughinsulating material over which the return conductor, which may be in theform of copper strips or the like, is wound. This return conductor hasalayer of insulating material extruded or otherwise applied thereto anda layer of magnetic tape is wound over this insulating material toshield the return conductor from high frequency electrica-ldisturbances, the insulation over the return conductor forming a shieldfor low frequency electrical disturbances. The cable is completed by theapplication of a jute covering and the usual cable armoring.

In a modification, the loading tape o1' strip may be applied diectly tothe return conductor but insulated therefrom, the insulation surroundingthe loading material as well as the return conductor in this case. Thisform of construction is advantageous in that it gives a higher seareturn inductance and of course the insulation tends to preventcorrosion of the loading material.

In another embodiment of thefinvention submarine cable terminal sectionYcomprises a main central conductor loaded and insulated in the usualmanner, but the return conductor in this case consists of separatelyinsulated conductors preferably wound with a long lay over theinsulation and loading material which is wound over these insulatedconductors, a layer of insulating material being applied over theconductors and the loading material. Alternatively, the insulation maybe applied to the insulated cable conductors and the loading materia-lapplied externally to the insulation. In a modification twoor morelayers of insulated return conductors maybe used, each layer beingloaded.

The invention will now be described with reference Y to the accompanyingdrawings which show Vembodiments thereof and in which similar referencenumerals indicate similar parts.

Fig. 1 shows a cross-section of a terminal 4 portion of va deep seasubmarine cable wherein the armor forms part of the return con! ductor;

Fig. 2 shows a partial section of a cable wherein the return conductoris enclosed within loading material and insulating material; V

Fig. 3 shows a modification of Fig. 2;

Fig. 4 shows a partial section of a cable wherein the return conductorsconsist of insulated wires;

Fig. 5 shows a modification of Fig. 4; Fig. 6 shows a telescopedlongitudinal view of the cable shown in Fig. 1; and

Fig. 7 shows a telescoped longitudinal View of the cable shown in Fig.5.

In Figs. 1 and 6, reference numeral 2 indicates the main cableconductor, 3 the usual magnetic loading material (surrounded in practiceby the usual pressure equalizing maferial, not shown), 4 the insulatingmaterial applied over the loading material, 5 a tough insulating tapeapplied over insulation 4, 6 the return conductor which may be in theform of copper'wires, but which in Fig. 1 is'shown as' copper strips ortape and which is preferably wound with a long lay. A layer ofinsulating tape 7 may be applied over conductor 6 and a layer ofinsulating material 8 is extruded or otherwise applied over theinsulated return conductor. The

wrapping of loading material is shown at 12. A preferred composition ofmagnetic loading material comprises about 7 81/2% nickel and the balancechiefiy iron, heat treated to have an initial permeability of about 2000or more. The usual jute cable covering is shown at 9 and the usual cablearmor wires at 10.

In the construction shown in Fig. l the armor 10 forms part of thereturn conductor, since in the central sections the returnV conductor 6is not usually loaded and insulated from the sea water and the armor; inthis manner parallel return current paths are provided through returnconductor 6 and the armor 10. In this case yit is preferable to load thearmor by surrounding it with a wrapping of magnetic material. To thisend wires or strips 11 of iron or other magnetic material, such as analloy of 7 81/2% nickel and the balance chiefiy iron, may be appliedover the armor 10. These loading or shielding wires 11 are wound aroundthe armor 10 with a short lay. By this construction the effectiveinductance of that part of the return current which flows through thesea water is increased and the return current is caused to flow chieflythrough the metallic armor wires 10 and through the highly conductiveconcentric return path 6.

In the construction shown `in Fig. 2 the return conductor is formedchiefly kby copper wires or strips 6, and in this case the loading tape12 may be applied over the insulating material 8.

Fig. 3 shows a modification of Fig. 2 in which the loading tape 12 isapplied directly over theinsulating tape 7 on the return conductor, andtherefore is in close proximity to the copper return conductor, and thisconstructionresults in giving a higher sea return inductance, and as theinsulation 8 is applied over the loading material, this is effectivelyprotected from corrosion.

In Fig. 4 the copper return conductor has the form of individuallyinsulated copper wires 13 which are applied over insulation 4 andinsulating tape 5 with a long lay. The wrapping of insulating tape 7 maybe applied over these conductors and the loading material 12 andinsulating material 8 may be applied thereover.

In Fig. 5 are shown two layers of individually insulated returnconductors 13 and 13', these being separated by insulating tapes 7 and 7and loading material 12. Wrappings of insulating tape are shown at 7, 7and 7 Loading tapes 12 are applied eX- ternally to the insulatedconductors 13.

In Figs. 6 and 7, those reference numerals which are identical withthose of Figs. 1 and 5, respectively, indicate identical parts. It maybe seen from these figures that the return conductors 6, (Fig. 6) 13 and13 (Fig. 7) are applied with a long lay and that the loading orshielding tapes 12 and 11 (F ig. 6) and 12 and 12 (Fig. 7) are appliedwith a short lay.

The above described cable constructions are more particularly applicableas end portions of long deep sea cables, and the insulation of thereturn conductors is effective to shield the circuit comprisingthecentral and/ or outer or return conductors from Very low frequencyelectrical disturbances, such as for example, currents of less than tencycles per second, and the magnetic material wrapped around the outerconductors is effective for shielding the circuit from higher frequencyinterference.

This type of shielding has the advantage over the generally employedsea-earth in that a higher ratio of received signal to noise is obtainedwhen the noise is that due to the thermal agitation of the electrons inthe cable conductors.

What is claimed is 1. A submarine cable comprising a continuously loadedcentral conductor and a return conductor continuously surrounded bymagnetic material, wherein at least part of the return conductor isinsulated to shield this part from low frequency electricaldisturbances.

2. A cable according to claim 1, wherein the return conductor comprisesin combination aconductor surrounding the main cable conductor and (b)the metallic armor of the cable.

3. A cable according to claim 1, wherein a sheath of insulating materialis applied over the concentric return conductor and a layer of magneticmaterial is applied over said insulation.

4. A cable according to claim 1, wherein a layer of magnetic material isapplied eX- ternally to the return conductor and a sheath of insulatingmaterial is applied over the return conductor and the magnetic material.

5. An armored sub-marine cable comprising a continuously loaded centralconductor and a concentric return conductor continuously surrounded bymagnetic material, wherein a part o-f said return conductor is formed bysaid armor and another part of the return conductor consists ofindividually insulated conductors having a layer of magnetic materialapplied thereto.

6. A submarine signaling cable comprising a single insulated outgoingconductor, a concentric return conductor surrounding said outgoingconductor, means external to said conductors for shielding them fromhigh frequency external disturbances, said means comprising a.v metallicsheath having a magnetic permeability at small magnetizing fo-rceshigher than about 400, and means for shielding said conductors from lowfrequency external disturbances, said means comprising a sheath ofinsulating material.

7. A cable as defined in claim 6 charactei-ized in this, that the shieldof magnetic material is provided underneath the sheath of insulatingmaterial.

8. In combination, in a medium conductive to parasitic currents of highand low frequency, an electrically insulated and continuously loadedcentral conductor, a second conductor surrounding said first mentionedconductor in the form of a substantially continuous and uniform sheath,a layer of magnetic material surrounding said sheath in a continuous anduniform manner for reducing the effect upon the conductors of saidparasitio currents of high frequency, and shielding means for reducingthe effect upon said conductors of said parasitic currents of lowfrequency, said means comprising a layer of insulating materialsurrounding said conductive sheath.

9. Combination as defined in claim 8 comprising an armor external tosaid conductive sheath, said armor forming a part of the returnconductor and being surrounded by a wrapping of magnetic material.

In witness whereof, I hereunto subscribe my name this 26th day of J une,1931.

OLIVER E. BUCKLEY.

